Unsaturated polyester resins modified with organic dibasic acid salts

ABSTRACT

Metal salts of alkanedioic and aromatic dibasic acids are used to improve one or more of the physical properties of certain thermoplastic and thermosetting resins, either before or after exposure to high temperatures.

0 United States Patent 1151 3,674,894

Economy et al. July 4, 1972 [54] UNSATURATED POLYESTER RESINS 58 Fieldof Search ..260/865, 75 U, 75 s MODIFIED WITH ORGANIC DIBASIC ACID SALTS[56] References Cited [72] Inventors: James Economy, Buffalo; Luis C.Wohrer, UNITED STATES PATENTS W Clarence 3,219,604 11/1965 Fischer..260/22 f 3,390,205 6/1968 Schnell et al. 1 Asslgneer E g p y Niagara3,557,042 1/1971 13111111118611 ..260/3 1.2

a s, Filed: y 1970 OTHER PUBLICATIONS [2 App. NOJ 46,568 Ak1ta et al.,Reinforced Plast1cs 4,2-5( 1958) Related U.S. Application Data PrimaryExaminer-Melvin Goldstein ll [62] Division of Ser. No. 751,647, June 24,1968, Pat. N0. Attorney K W Browne 3,567,689, which is a division ofSer. No. 353,266, March 19, 1964, Pat. N0. 3,418,273. [57] ABSTRACTMetal salts of alkanedioic and aromatic dibasic acids are used [52] U.S.Cl ..260/875, 1 17/264, 260/ 17.3, to improve one or more of thephysical properties of certain 39 260/40 260/ 260/57 thermoplastic andthermosetting resins, either before or after 260/67 exposure to hightemperatures.

260/231 R [51] Int. Cl ..C08f 43/00, C08f43/02 7 Claims, No Drawingsapplication, Ser. No. 353,266, filed Mar. 19, 1964 and now US. Pat. No.3,418,273.

The inventions herein relate to polymer blends derived from divalentmetal salts of dibasic organic acids, to mixtures useful in theproduction of these blends and to processes for their production.

organometallic salts have been used in a wide variety of polymercompositions, e.g., as fillers, colorants, opaque agents, dullingagents, inhibitors, polymerization catalysts, light stabilizers etc. Theorganometallic salts of this invention are used to improve one or moreof the physical properties of several classes of polymers, for the mostpart the strength thereof, either initial or after exposure to hightemperatures. However, the property which is improved and the extentthereof depends upon the class of polymer involved, each classbenefiting uniquely. For example, with the phenol-formaldehyde novolaks,a marked improvement in tensile strength is obtained whereas withcellulosic ethers significant increase in elongation is the most markedimprovement obtained. Because the organometallic salts employed in thepolymeric compositions described herein have an effect which differsunpredictably from polymer class to polymer class, each class will bedealt with individually hereinafter.

The polymers employed in the novel compositions fall generally into twobroad classifications, i.e., thermosetting resins or plastics includingthe phenolics, ureas, melamines and polyesters, and the thermoplasticresins, including polystyrenes, polyacrylates and cellulose ethers andesters. The elastomers, e.g., natural rubbers, polybutadienes,silicones, linear polyurethanes, are not resins or polymers within themeaning of the terms as used herein. Polyvinylidene chlorides, polyvinylchlorides and like plasticized polymers are also not within the scope ofthis invention. The organometallic metal salts employed in the novelcompositions described hereinafter are divalent metal salts of dibasicorganic acids selected from the group consisting of alkanedioic andaromatic carbocyclic dibasic acids. The metal cation portion ispreferably those of the group II metals of the periodic table, desirablyof an atomic number from 12-56, inclusive, and desirably also of thegroup "A metals. Calcium is the metal of choice. The dibasic acidspreferably contain from four to 12 carbon atoms, more preferably fromsix to 10.

The saturated alkanedioic acids are preferably of six to 12 carbonatoms, e.g., of the formula l-lOOC-(CI-l ),,COOH, in' which n is 6 to12. The aromatic carbocyclic dibasic acids are preferably of six to 12carbon atoms and are preferably disulfonic or dicarboxylic acids.Especially preferred are sebacic acid and the phthalic acids. Calciumsebacate, calcium phthalate, calcium isophthalate and calciumterephthalate, are the organometallic salts of choice with calciumphthalate preferred over all others.

A simple divalent metal salt of a dibasic organic acid can be employedor a mixture of such salts, improved results being sometimes obtainedwith such mixtures. The salts are employed in amounts from about 2percent to about 25 percent, preferably about percent to about percent,e.g., 5 to 15 percent, calculated on the weight of the organic polymeror prepolymer employed. The optimum and minimum and maximum amounts willvary from polymer to polymer. As a general rule, however, amounts below2 percent have relatively little effect and amounts above percent havelittle favorable effect and produce adverse effects as the percentage isincreased. About 5 to 10 percent is usually the amount of choice.

These organometallic salts can be formed in situ when the polymer blendis formed by milling or by polymerization at elevated temperatures,e.g., above about 100 C. and more preferably about 150 C. or above, bythe use of a mixture of an anhydride or acid and a hydroxide or oxide ofthe metal in amounts which will react at elevated temperatures to formthe desired amount of the selected organometallic salt, e. g., a mixtureof phthalic anhydride and calcium oxide.

The examples set forth hereinafter are illustrative only and are not tobe construed as limiting the inventions.

A. Pl-IENOL-FORMALDEHYDE POLYMERS According to this invention, apolymerizable composition is provided comprising a phenolic prepolymerand from about 2 percent to about 25 percent by weight thereof of adivalent metal salt of a dibasic organic acid as described above. Thesecompositions are polymerized by the process of this invention to formnovel resite and cured novolak polymeric compositions having improvedthermal stability and other enhanced properties useful in phenolicpolymers.

Four basic improvements in physical properties have been observed whenan organometallic salt as described herein is incorporated into the mixused to form the phenolic resin, i.e., improved thermal stability,tensile strength, and improved resistance to water and aging. Suchimprovements allow considerable flexibility in solving such additionalproblems as ease of processing and dimensional stability. For example,because of the increased strength from use of the herein described metalsalts, a lower strength phenolic with a higher flow can be used. Thisleads to a process improvement by increasing flow rate in the mold.Similarly, this improved strength allows the use of shorter asbestosfibers in reinforced phenolics leading to better processability and useof a lower cost fiber.

The improvement in water resistance results in improved dimensionalstability and surface properties such as electricals, etc.

The improvement in thermal stability and aging extends the usefulness ofphenolic resins into higher temperature applications. Thus, suchmodified phenolics find use at temperatures 50-75 C. above the presenttemperature limitations for phenolics.

The phenolic prepolymers of the polymerizable compositions of thisinvention include novolaks, preferably unmodified, resitols and resoles.

Novolaks are acid catalyzed phenol resins having a phenol/formaldehyderatio greater than 1, exhibiting very little, if any, cross-linking andare permanently fusible and soluble. Their mean molecular weight isusually less than 1,000. They can react under alkaline conditions, heatand pressure to form methylol groups which then yield resite typeproducts.

Resoles are A-stage alkaline catalyzed resins soluble in alkalies,alcohols, ketones and to some extent water. They have a high hydroxylcontent and a relatively low molecular weight.

Although preferably unmodified, the phenolic prepolymers can be modifiedwith the conventional modifiers, e.g., chromium oxide.

These phenolics are preferably phenol-formaldehyde polymers althoughcresol or part cresol and other alkyl phenols and other aromatic hydroxycompounds can be used as the precursor as well as most active aldehydes,e.g., acetaldehyde, glyoxal and furfural.

The polymerizable compositions of this invention can include modifyingagents, e.g., glycerol, fatty acids and alkyd resins, and fillers andextenders, e.g., wood flour, walnut-shell flour, asbestos, cellulosic orglass fibers, rubber, carbon, mica, oxides, silicates and carbonates,including zinc oxide, barium oxide, calcium oxide, titanium oxide, zincoxide, calcium carbonate, diatomite, alumina, silicon carbide, bariumsulfate, etc. Because the property enhanced the most is thermalstability, the heat resistant extenders and fillers conventionallyemployed in high temperature phenolics are the fillers of choice.Articles reinforced with glass, asbestos, paper or cotton cloth, mats orsheets or fibers employing a polymerizable composition of this inventionare especially preferred embodiments of this invention.

The preferred cured articles of this invention are formed from about5-80 parts by weight of phenolic resin, about l-l 5 parts by weight oforganometallic salt and about 94-5 parts by weight of filler, preferablyl to 60 of the re sir l to 109! the salt and 89 to 30 offiller.

The usual curing techniques and procedures are employed in the processof this invention. Both wet and dry formed phenolic prepolymers can beemployed. Usually the prepolymer is employed as a finely ground powder.As with conventional phenolic resins, fine particle size and thoroughmixing of ingredients are desirable.

The novel polymerizable compositions can be used to form laminates,compression cast and transfer molded articles as well as jet molded andextrusion formed articles.

The following are examples of phenolic blends of this invention and thecured resins formed therefrom.

Example 1: Unmodified Phenolics (Unfilled) Control samples were preparedby mixing 400 g of an unmodified novolak with a molecular weight (M,,)of 839 and a hexamethylene tetramine content of 9.3 percent and amelting point of l02-I08 C., with 100 g CaO in a Waring blender for twol-minute periods at a speed of 17,000 rpm. An 8 X 8 4; inch frame moldwas then charged with 260 g of this blend and a plaque was compressionmolded for one-half hour at 171 C. 1 55 and 1,800 psi 1 10 percent. ASTMD-638 specimens, Type 1, were cut from this plaque.

Samples were also prepared using a mix of 360 g of the above-describednovolak, 90 g of CaO and 50 g of one of the following:

Cl CaCO (comparative sample) C-2. Calcium valerate (comparative sample)C-3. Calcium hexanoate (comparative sample) C-4. Sebacic acid(comparative sample) 1a. Calcium sebacate 1b. Calcium isophthalate 1c.Calcium terephthalate 1d. Barium sebacate 1e. Zinc sebacate 1 f. Calciumazelate The tensile strength of all samples was tested according to ASTMD-638, before and after heat aging for 24 hours in a forced air oven at285 C. i 5. The test results are summarized in Table la.

and 10 parts of hexamethylene tetramine were intimately mixed and groundto pass through a 100 mesh sieve. The sieved material was pressed into atest plaque at 166 C./1,000 psi for 1 hour followed by a post cure at150 to 160 C. for 6 hours. After curing the test piece was reground,screened through a 60 mesh sieve and its weight loss characteristics inair compared with a control test piece, not containing the barium salt,treated in the same manner. The percentage weight losses of theunmodified versus the modified novolak resins Calculated on organicportion Example 2: Unmodified Phenolics (Asbestos filled) a. Controlsamples were prepared by blending 300 g short fiber asbestos, (QuebecAsbestos Mining Association 6D20). 560 g. unmodified novolak having a M,of 839, a melting point of 102-l08 C. and a hexamethylene tetraminecontent of 9.3 percent, and 140 g. CaO in a sigma arm mixer operating ata speed of 35.6/59.6 rpm for 1 hour. ASTM D-638 test specimens, Type 1,one-eighth inch thick, were compression molded for one-half hour at 171C. i 5.5 and 1,800 psi 3 10 percent.

b. Using the same procedure, novolak and asbestos test specimens wereprepared from the following compositions: 300 g short fiber asbestos,480 g of the above-described TABLE novolak, 120 g CaO and 100 g calciumsebacate.

The tensile strength of Examples 2(a) and 2(b) specimens were testedaccording to ASTM D-638, before and after heat aging for 6 and for 24hours in a forced air oven at 285 C. 2; 5. The test results aresummarized in Table I1. 24 hrs. 285C. Original of TABLE II Sample psi ofControl psi Control Control 9300 100 2000 100 cu (CaCO 9200 99 900 45 ahc 2 (Ca val erate) 5600 60 800 40 original 5 253 i' C-3 (Ca hexanoate)5600 200 10 sample Strength 6 hours 24 hours C-4 (Sebacic acid) 6100 66700 35 1a 8800 95 5900 295 117 12400 133 7800 390 28 (Comm!) 6800 psi4500 10 12000 129 3200 160 2b 8300 psi 7400 7000 if 2388 g; 32% :38 60of control) 122% 164% 1f 8400 90 4200 210 Example 3: UnmodifiedPhenolics (Asbestos filled) lg. Following the procedure of Example la,other samples The procedure of Examples 2(a) and 2(b) was followed wereprepared in which the amount of calcium sebacate was varied from 25 100g(5 20 percent) with corresponding variations in the amount of novolak.The original tensile strength of the samples varied from 78 -95 percentof the control but the tensile strength after 24 hours at 285 C. variedfrom 230 3 10 percent of the control sample (without the ca1- ciumsebacate). Amounts above about 20 percent calcium sebacate gave noadvantage in strength.

lh. eighty parts of a novolak resin of 740 molecular weight, 10 parts ofthe barium salt of a meta-benzene-disulfonic acid cept that long fiberasbestos (Quebec Asbestos Mining Association 3R-l2) was substituted forthe short fiber asbestos. Substantially the same results are obtained asin 2( b) at both 10 percent and Spercent calcium sebacate levels.

Example 4: Unmodified Phenolics grit-filled) a. Control samples wereprepared by mixing 880 g A1 0 abrasive grain having an average grainsize of 2.05 mm with 30 g of an NaOl-l catalyzed resole having aformaldehydezphenol ratio of 0.5 and a viscosity of 1,0002,000 cps. Thismix was then blended with 90 g of an unmodified novolak having an M of765, a melting point of 95-l00 C and a hexamethylene tetramine contentof 9.0 percent. Dog-bone shaped test specimens having a minimum crosssection of l X V; were cold resins and mixtures thereof, and from about2 percent to 25 percent of the weight of the amino-formaldehyde compoundof a divalent metal salt of a dibasic organic acid as described above.

pressed to a structure having 19.3 percent by volume voids. 5 Theamino-formaldehyde Prepolymers Preferred for the These test samples werecured in a forced air oven for 8 hours Polymerizable compositions ofthis invention are the at programmed temperatures which reached a peakof 180 C. melamine formaldehyde P p y especially those wherein b. Usingthe same abrasive grain and .phenolic resins, sum the ratio of melamineto formaldehyde is about 1:2 to 1:3, ples were prepared i hi h 9 g fthehovolakwas Substituted particularly the novolaks. The most useful arethose classiby9 gcalcium sebacate. 10 fled in the trade as compressionor transfer molding grades The tensile strength of the samples wastested at 24 and me|aminejf0Fm3ldehyde Compounds- 260C. Additionalsamples were heated to 300Cforone-half Anfincfomaldehyde p y are for themost P hour prior to testing at 24 and 260 C. Other samples were P y inconjunction with a carbohydrate finer, -gw Wood of boiled in H O for 24hours or soaked in H O for 7 days prior to l 5 walnutisheu flour,Preferably alpha-cellulose, P rayon testing. The test results aresummarized in Table III. comm woven or hoh'woven form to form lamlnatesand TABLE III Tensile Strength, p.s.i.

)4 hr. post cure at 300 C. 24 hrs. 7 day 177 cure, 200 C. 24 0. 260 C.boiling soaking 24 0. test te test test in H in H20 Sample:

4(a) (control) 1,414 695 778 587 826 1,292

Percent of control 145 133 l 171 151 118 164 Example 5: PhenolicLaminates castings. Generally they are available as the monomer orlowstage resins or prepolymers. Although the aniline-formal- Seven mllpaper was impregnated l a NaoH dehyde compounds produce thermoplasticresins, they are catalyzed resole having a formaldehydezphenol ratio of1:2, a useful in many of the same areas of applications as the thenvlscoslty of 6,000 cps and 3-S0l1d content of 70 percent, at a mosetfingurea thiourea and melamine resins. weight ratio of paper to resln(sollds) of 1:1. The paper was The novel minoformaldehyde polymerizablecomposi mlpregnated wnh resole by lmmersmg the paper m me tions,especially the urea and melamine compositions, are usemlX for l to 3mmutes- The Wet P p was thfzn Squeezed ful for forming laminates, e.g.,by dipping sheets or fabric in through a slit to obtain the desiredpick-up. The impregnated the polymerizable Solution containing apolymerization paper was then predried at room temperature for 2 hours.Catalyst, removing the excess drying under controlled ify was completedin ch'culatlng 5 tions to partially set the resin and laminating amultiplicity of layers under heat and high pressure.

The impregnated P p was cut into 9 X 9 inch q 40 They are also useful toform molded articles, using about Twelve of these squares were used toform a laminate with the 25 5 percent f a fl or eellulosie material as afill and sheets alternating perpendicularly with respect to machining husual h d f wi these thermosettihg l i i direction. The laminate wasmolded between chromium h absence of h orgahometahie le If h ldi platedmetal plaques for one-half hour at 164C. i 3 an position is suppliedaspills or tablets, the organometallic salt is 1,000 psi. The sheetswere then cooled to room temperature preferably thoroughly blended withthe amino-formaldehyde in 5 minutes under pressure. compound before theformation of the pills or tablets.

b. Other sheets of the 7 mil Kraft paper were impregnated Thepolymerizable compositions of this invention are also with a dispersionformed by blending 1 kg of the aboveuseful in producing foams which areof particular value, e.g., described resole with 78 g of calciumisophthalate in a paint as insulation, because of improved tensile andflexural mill, at the same 1:1 weight ratio. The laminates were moldedstrength. For example, a water soluble urea-formaldehyde and testspecimens prepared as described above. The test resin containing 2 to 25percent by weight of a divalent metal results aresummarized in Table IV.salt of an organic acid, calculated on the weight of theureaformaldehyde compound and wood flour or other filler, TABLE IVbeaten into a foam and cured by addition of suitable catalysts anddried, makes foams both above and below 0.05 density of greater strengthand resistance to cracking than the corresponding foams in which thesalts are omitted. Tensile strength after heat The following illustratesthe amino-formaldehyde blends of aging for 24 hours at 200C thisinvention and their use. Samples psi Control Example 6:Melamine-Formaldehyde Blends 5a 5830 208 5b (Control) 2800 too a. Twohundred and twenty-five g of an alpha-cellulose-containingmelamine-formaldehyde molding compound having a density of 1.5 (Cymel1077, American Cyanamide) was homo enized with 25 calcium tere hthalateon a hammer Coniparable results are obtained by .subspwtmg banum mill.1% chromium plate d steel mold of the size 8 it X8 /2 X is or calclumsalt of meta-benzene sulfonlc acid for the dlcarboxh h d th d th d licacid salts employed in Examples 1 to 5. me was coarge e l an e mo mgCarrie y out at 167 C. and 2,000 psi pressure over a period of 3AMINOFORMALDEHYDE POLYMERS minutes allowing a pump-breath after thefirst minute. The

plaque was ejected after cooling down to 49 C. Test According to thisihvehtic'h a P y composition P specimens for the determination of thetensile strength vided by curing a mixture comprising anamino-formaldehyde (ASTM 13. 33 Type 1 fl strength (ASTM 490 fusibleresin, e.g., melamine-formaldehyde, urea-formaland d fl ti temperature(ASTM 40 were prepared dehyde, thiourea-formaldehyde andaniline-formaldehyde and tested.

Using the same procedure, test specimens were also prepared fromcompositions in which the calcium terephthalate was replaced by the sameamount of calcium isophthalate, azelate or sebacate or the salt wasomitted as a control.

The test results are summarized in the following Table V.

TABLE V Flexural Deflection Tensile Strength Temp. "C Samples Strengthpsi psi Hardness 64 Ca Terephthalate 9,600 19,900 220 6b Ca lsophthalate10,800 20,500 220 6cCaAzelate 11,100 213 6d Ca Sebacate 9,930 17,900 2006e Control 6,670 15,200 210 Comparable results are obtained bysubstituting an equivalent amount of calcium phthalate or calcium orbarium meta-benzene disulfonic acid for the dibasic acid salts employedin Examples 6(a) to 6(d).

c. POLYESTERS According to this invention, a polymerizable compositionis provided comprising a polyester prepolymer containing ethylenicunsaturation and from about 2 percent to about 25 percent by weight ofthe prepolymer of a divalent metal salt of a dibasic organic acid asdescribed above.

The polyester prepolymers employed in the polymerizable compositions ofthis invention are the unsaturated ester class of casting andlow-pressure laminating resins, i.e., polyester prepolymers havingunsaturated ethylenic groups. These polyesters polymerize through carbonto carbon bonding to form cross-linked thermosetting structures. Theyare generally prepared by the use of an unsaturated dior polybasic acid,e.g., maleic acid, or an unsaturated alcohol, e.g., allyl alcohol orboth, as a portion of the esterification mixture. Another unsaturatedcompound, e.g., up to 50 percent styrene, can be included in theprepolymer mixture to form a copolymer, along with the halogenated andantimony compounds conventionally included in such prepolymer mixtures.

These polyesters are preferably condensation products of dior polyolsand dior polycarboxylic acids, e.g., the polyester formed by theesterification of aliphatic glycols, e.g. ethylene glycol, propyleneglycol, a polyethylene ether glycol, etc., with an aliphatic or aromaticdicarboxylic acid or mixture thereof which provides the ethylenicunsaturation in the acid moiety, e.g., a mixture of phthalic and maleicanhydrides. As stated above, the mixture can include other polymerizablemonomers or polymers containing ethylenic unsaturation, e.g., styrene,to copolymerize with the unsaturated groups in the polyester and modifythe properties of the polyester. As used to prepare thermosettingresins, they are generally viscous liquid prepolymers or contact resinswhich, when mixed with an appropriate catalyst, usually a peroxidecatalyst, spontaneously set to a hard resin. For further description ofthis class of materials, see U.S. Pat. Nos. 2,370,565; 2,370,566;2,370,572; 2,370,573; 2,370,574; 2,370,578; 2,384,115; to 2,384,125.These polyester forming mixtures are conventionally employed inconjunction with a fibrous material, e.g., spun glass filaments orfabric to form large articles and self-supporting structures. See U.S.Pat. Nos. 2,276,004; 2,337,007; 2,342,988; 2,392,108; 2,392,707; and2,394,730.

Polyesters are a relatively expensive class of resins. Their widespreaduse is therefore a tribute to their versatility. It is highly desirableto employ inexpensive fillers or extenders to reduce their cost.However, it is difiicult to provide extenders which retain the desiredqualities of polyester resin.

it has now been found that divalent metal salts of the dibasic organicacids described above act as extenders for polyesters which not onlyretain their desirable properties but often these properties areenhanced, particularly their tensile strength, which is a highlyunexpected result.

The divalent salt is employed in an amount between about 2 and 25percent, preferably within the range of about 5 to 10 percent. Theselected salt, preferably calcium phthalate, and the selected polyesterprepolymer, preferably a styrene modified liquid polyester prepolymer,are thoroughly mixed prior to catalyzed curing or polymerization.Conventional casting, molding and polymerization techniques can beemployed.

The following is illustrative of the polyester blends of this invention.

Example 7: Polyester Blends a. Three hundred g of a styrene-modifiedgeneral purpose (ethylene glycol-phthalic and maleic anhydride)polyester having a viscosity of 2,700 cps/25 C. (Brookfield) wascatalyzed with 5.6 ml of a 60 percent solution of methylethyl ketoneperoxide in dibutyl phthalate. Thirty g calcium adipate was added andthe mass was thoroughly mixed. This mix was cast into an 8 X 8 X A inchglass mold and cured in a water bath at 50 C. for 17 hours. A rigidpolyester sheet was obtained. This sheet was post-cured at C. for 24hours. Test specimens (according to ASTM D-638, size No. l) were cut.

Using the same procedure, test specimens were also prepared employingthe same polyester resin and catalyst in the same amounts butsubstituting 30 g calcium terephthalate for the calcium adipate oromitting the salt completely as a control.

The tensile strength of these specimens was tested according to ASTMD-638. The test results are shown in TAble Vl.

Comparable results are obtained by substituting an equivalent weight ofcalcium phthalate or sebacate or calcium or barium meta-benzenedisulfonic acid for the dibasic acid salt employed in Examples 7(a) and7(b).

D. POLYSTYRENES According to this invention, there is provided mixturesof polystyrene and from about 2 percent to about 25 percent by weightthereof of a divalent metal salt of a dibasic organic acid as describedabove. These mixtures can be formed into shaped articles of manufacturehaving improved tensile strength, either before or after heat aging,compared with the identical shaped article formed entirely of theselected polystyrene.

The shaped article of manufacture can be formed by extrusion, molding,machining, casting to form sheets or oriented films, foam casting ormolding, e.g., to form oriented foamed sheets by balloon extrusion. Theconventional styrene polymerization techniques can be used to form thepolystyrene. Although the compositions of this invention are ordinarilyproduced by blending the selected polystyrene with the selectedorganometallic salt, they can also be formed by polymerization ofstyrene in the presence of the organometallic salt, e.g., by batch mass,solution or emulsion or suspension polymerization or continuous masspolymerization in which the styrene monomer and organometallic salt arethoroughly mixed before or during polymerization.

Inna

When polystyrene is employed, a heat resistant grade, e.g., a highpurity homopolymer or a copolymer formed with up to about 35 percentvinyltoluene, is preferred. These are referred to in the trade asinjection molding or extrusion grade.

strength is improved. Inert fibrous fillers, e.g., glass filament orfibers or asbestos fibers are desirably incor orated into the shapedarticles of manufacture.

The following is illustrative of the polystyrene blends of thisinvention.

Example 8: Polystyrene Blends a. One hundred and ninety g of a heatresistant polystyrene with a melt flow of L04 g per minutes (ASTMD-1238, condition G) and a density of 1.06 (Dylene 9) was milled with 10g calcium isophthalate on a two roll mill for 5 minutes. The front andback roll were kept at 167 C. The mix was compression molded at 177 C.and 3,000 psi, using a 6 X 6 X one-sixteenth inch mold. Test specimenswere cut and the tensile strength of these specimens was tested,according to ASTM D-638, in which samples are tested, before and afterheat aging in a forced air oven.

Samples 8(b) (2 percent calcium isophthalate) and 8(c) (no calciumisophthalate) were prepared and tested using the same procedure.

The results are given in the following TableVIl.

TABLE VII Tensile Strength After heat aging Initial 48 hours at 195F ofof Samples psi Control psi Control 811 5% Ca Isophthalate 6360 134 60001 19 8b 2% Ca lsophthalate 4870 103 5650 l l2 8!: Control 4750 100 5050r 100 Comparable results are obtained by substituting an equivalentamount of calcium phthalate or sebacate or calcium or bariummeta-benzenedisulfonic acid for the calcium isophthalate employed inExamples 8(a) and 8(b).

E. ACRYLATES According to this invention, there is provided mixtures ofa polyacrylate and from about 2 percent to about 25 percent by weight ofa divalent metal salt of a dibasic organic acid as described above.These mixtures, when hot blended, can be formed into shaped articles ofmanufacture having improved resistance to thermal degradation comparedto corresponding articles formed solely from the polyacrylate.

The polyacrylate compositions can be formed into shaped articles ofmanufacture, by e.g., molding extrusion casting or machining, in thesame manner as conventional polyacrylates.

The polyacrylates employed in this invention are the thermoplasticpolymers of esters of acrylic acid and methacrylic acid, preferably thelower-alkyl esters of one to four carbon atoms and preferably the methylester, and mixtures or copolymers thereof. Polymethyl methacrylate andpolymethyl acrylate are the polymers of choice.

The compositions of this invention are generally formed by blending theselected organometallic salt with the melted polyacrylate until auniform mixture is obtained, e.g., by hot milling. The compositions aregenerally substantially free from other organic polymeric materials.However, when a calcium phthalate is employed, a copolymer ofmethylmethacrylate and, e.g., 10-40 percent of styrene or acrylonitrilecan be used with improved results. Conventional fillers and reinforcingfibrous materials can also be incorporated in the compositrons.

The following illustrates the polyacrylate blends of this invention.

Example 9: Polymethyl Methacrylate Blends a. 142.5 g of a heat resistantpolymethyl methacrylate with a density of 1.19 and a refractive index.of L49 (Rohm & Haas Plexiglas V) was milled on a two roll mill with 7.5g calcium isophthalate (5 percent) at 177 C. for 5 minutes. The blendwas molded in a 6 X 6 X one-sixteenth inch mold at 177 C. and 4,000 psipressure.

Test specimens were cut and the tensile strength of these specimens wastested, according to ASTM D-638, in which samples were tested before andafter heat aging (48 hours at C. in a forced air oven).

Samples 9(b) and 9(0) were made using the same procedure but employinglesser amounts of calcium isophthalate. ln sample 9(d) calciumterephthalate was substituted. Sample 9(e) was the control with no acidsalt. The test results are summarized in the following Table VIII.

Comparable results are obtained by substituting an equivalent weight ofcalcium phthalate or sebacate or barium meta-benzenedisulfonic acid forthe dibasic acid salts em ployed in Example 9(a) 9(d).

F. CELLULOSE DERIVATIVES According to this invention, cellulosederivative mixtures are provided comprising a thermoplastic ether orester of cellulose and from about 2 percent to about 25 percent of adivalent metal salt of a dibasic organic acid as described above. Thesecompositions, especially when formed into shaped articles of manufacturesuch as sheets, films, filaments, etc., have superior elongation thanthe corresponding cellulose derivative in the absence of theorganometallic salt. The improvement is particularly noticeable afterexposure to elevated temperatures. They thus have improved utility inthe areas of use for cellulose derivatives, e.g., films, sizingmaterials, etc. where good elongation is desired.

The cellulose ethers include the aliphatic ethers, e.g., the watersoluble methyl, ethyl, a-hydroxypropyl, hydroxyethyl, carboxymethyl andcarboxyethyl ethers, and the organic solvent soluble ethers, e.g.,propyl, butyl, amyl ethers and mixed ethers, e.g., methylhydroxypropylcellulose.

The cellulose esters include the aliphatic, aryl, and inorganic esters,e.g., cellulose acetate, cellulose propionate, cellulose butyrate,sodium cellulose sulfate, nitrocellulose, sodium cellulose phosphate,mixed esters, e.g., cellulose acetate butyrate, cellulose acetatepropionate, of conventional degrees of substitution. Preferredderivatives are cellulose acetate and ethyl cellulose.

Example Ethyl Cellulose Blends a. One hundred and eighty g ethylcellulose with a density of 1.11 and a flow grade (ASTM D-569) of M-MH(Ethocel 890) was milled with g calcium isophthalate on a two roll millfor 8 minutes. The front roll temperature was kept at 143 C. and theback roll temperature at 93 C.

A 6 X 6 X 1/16 inch mold was charged with 100 g of the blend and themolding was carried out at 177 C. and 4,000 psi pressure.

Samples 10(b) 10()) were made using the same procedure but employingvarying amounts of calcium isophthalate, or lead isophthalate, bariumsebacate or omitting the organic salt as a control.

Test specimens were cut and the tensile strength of these specimens wastested, according to ASTM D-638, in which samples were tested before andafter heat aging (48 hours at 105 C. in a forced air oven). The testresults are summarized in he Q 1Qw asB'3 s=lX.- .s

10(1) control Example 1 l: Cellulose Acetate Blends a. One hundred andsixty g of a cellulose acetate with a density of 1.29 and a flowtemperature of 338 F. (ASTM D-569) was milled with 40 g calciumisophthalate on a two roll mill for 5 minutes. The front rolltemperature was kept at 160 C. and the back roll temperature at 155 C.

A 6 X 6 X l/l6 inch mold was charged with 100 g of the blend. A plaquewas molded at 182 C. and 4,000 psi pressure. Samples (b) (h) wereprepared using the same procedure but varying the amount of calciumisophthalate, substituting barium sebacate or zinc sebacate or omittingthe salt for a control. The yield strength of these blends is shown inthe following Table X.

TABLE X lnitial Yield Strength Samples psi Control 11:: 20% Calsophthalate 6870 131 [lb 10% Ca lsophthalate 6770 129 55% eli rl m.--6.5 9., 12s 1 1d 2% Ca lsophthalate 6300 1 le 1% Ca Isophthalate 6400122 1 1 f 5% Ba Sebacate 6550 1 1g 5% Zn Sebacate 6450 123 1 1): Control5250 100 The 20 percent calcium isophthalate had notably superior yieldstrength after heat aging at 93 C. for 84 hours.

Comparable results are obtained by substituting an equivalent weight ofcalcium phthalate or calcium or barium meta-benzene disulfonic acid forthe dibasic acid salts employed in Examples l0(a)10(e) and l 1(a) 11(3).

' We claim:

1. A polymerizable composition consisting essentially of a polyesterprepolymer containing ethylenic unsaturation and from about 2 percent toabout 25 percent by weight thereof of a divalent Group 11A metal salt ofa dibasic organic acid selected from the group consisting of saturatedalkanedioic acids, aromatic carbocyclic dicarboxylic acids, and aromaticcarbocyclic disulfonic acids.

2. A composition according to claim 1 wherein the prepolymer is astyrene modified prepolymer. v

3. A composition according to claim 1 wherein the salt is a Group 11Ametal salt of a carbocyclic aromatic dicarboxylic acid.

4. A composition according to claim 3 wherein the acid is a phthalicacid.

5. A composition according to claim 3 wherein the metal salt is acalcium salt.

6. A composition according to claim 3 wherein the salt is a calciumphthalate.

7. A polymerizable composition consisting essentially of a styrenemodified polyester prepolymer containing ethylenic unsaturation and fromabout 5 percent to about 15 percent, calculated on the weight of theprepolymer, of a calcium phthalate.

i l l

2. A composition according to claim 1 wherein the prepolymer is astyrene modified prepolymer.
 3. A composition according to claim 1wherein the salt is a Group IIA metal salt of a carbocyclic aromaticdicarboxylic acid.
 4. A composition according to claim 3 wherein theacid is a phthalic acid.
 5. A composition according to claim 3 whereinthe metal salt is a calcium salt.
 6. A composition accordiNg to claim 3wherein the salt is a calcium phthalate.
 7. A polymerizable compositionconsisting essentially of a styrene modified polyester prepolymercontaining ethylenic unsaturation and from about 5 percent to about 15percent, calculated on the weight of the prepolymer, of a calciumphthalate.